VMS DECwindows Device Driver Manual

The "VMS DECwindows Device Driver Manual," published in December 1988 for VMS Version 5.1, serves as a comprehensive guide for system programmers creating and understanding device drivers for DECwindows on VMS workstations. It primarily focuses on writing drivers for input devices connected to VAX workstations, detailing the software's architecture, components, and functionalities.

Key areas covered include:

• DECwindows Architecture: An overview of the X Window System-based environment, including servers, device drivers, network protocols, and programming libraries, with driver interaction primarily through Xlib and Toolkit routines.
• Driver Modules: A detailed explanation of the modular driver structure, encompassing Class Input, Port Input, Output, and Common drivers, along with their inter-module communication methods.
• Interfaces: Description of the two main driver/server interfaces: a shared input event queue (including a motion history buffer) for time-ordered input events, and the $QIO (Queue I/O) interface for device initialization and information requests.
• Driver Routines and Data Structures: In-depth information on the routines, macros, and data structures necessary for writing port input drivers (handling hardware interrupts and serial line characteristics), class input drivers (decoding serial data into X11 event packets and manipulating the input queue), and common drivers (device-independent processing and $QIO services).
• Output Driver: Details on managing graphics, windowing requests, video controllers, and $QIO services for output.
• Reference Appendices: Extensive documentation of DECwindows I/O subsystem data structures (such as Device Information Block, Input Buffer Control Block, Unit Control Blocks, and various vector tables) and device driver macros to ensure consistency and simplify coding.

This manual is essential for developing and maintaining device drivers for DECwindows environments on supported VAX workstation families.